In an optical wavelength division multiplex (WDM) transmission system, multiple optical transmission apparatuses are coupled to one another, and an optical wavelength multiplex signal obtained by multiplexing optical signals having different light wavelengths is transmitted among the optical transmission apparatuses.
The related art is disclosed in Japanese Laid-open Patent Publication No. 2014-7564 and Japanese Laid-open Patent Publication No. 2012-147151.